The direct reduction of iron oxide to metallic iron has become a worldwide reality, and direct reduced iron is a commercially accepted feed material in steelmaking.
Direct reduced iron, or sponge iron, is particularly well suited for electric arc furnace technology. It is not well suited as the principal feed material for other steelmaking furnaces, such as the bottom blown oxygen process, which require hot metal or molten metal, as feed material. At present, such hot metal is produced commercially only by means of blast furnaces which are inherently economically restricted to the availability of coking coal and to integrated steelmaking installations. It is, therefore, desirable to produce molten iron by direct reduction means which are economically suitable for small steelmaking plants and are independent of the use of coking coal.
The present invention accomplishes this end by (a) producing hot particulate direct reduced iron from particulate iron oxide in an efficient counterflow shaft furnace, (b) discharging the hot particulate iron into a melter containing a bath of molten iron, (c) injecting coal and oxygen into the molten bath to supply heat to melt the particulate iron and gasify the coal, and (d) introducing the hot melter off gases into the shaft furnace to reduce the iron oxide. The process is simple, efficient, nonpolluting, economical for small steelmaking installations, and suitable for use with noncoking coals which are available worldwide.